206 IOWA STUDIES IN NATURAL HISTORY 
raised ridges extending directly across them parallel to the long 
axis of the body, and each plate is strongly keeled in its center. 
The anterior plate is very conspicuous, its back border elevated 
centrally into a sort of shallow beak and its surface marked by 
very prominent, nodulated ridges radiating from the beak to the 
rounded front border, giving a fan-like effect. The girdle is 
covered with small granular spicules and the pleura of the valves 
bear rounded nodules on their edges, but are otherwise quite 
smooth. The foot is long and narrow and occupies a relatively 
small space, the shell extensively over-lapping it on each side; the 
ctenidia are not visible without dissection. In one specimen the 
foot is reduced to a mere strip. 
Still another chiton from Rakino is rather clear light gray with 
a series of very dark, almost black spots on the middle of each 
plate where the keel usually is and similar dark blotches almost 
bar-like, extending across the mantle, the latter covered with 
diamond shaped spicules. The foot is much larger and broader 
than in the species last mentioned. 
The most striking thing in the collection of Echinodermata 
from Hauraki Gulf is the entire absence of Echinoidea, for not a 
single sea-urchin was found. A very fine star-fish brought in by 
a trawler was turned over to me. I am unable to even approxi- 
mately identify this form as it will go into no family description 
which I can find. It has five short triangular rays and a very 
large disk. The spread measures nine inches and the disk, four 
inches across, is almost flat and very slightly vaulted. At the tip 
of each ray are two very conspicuous smooth, polished bean-shaped 
plates, in contact at their distal parts. The dorsal surface of the 
rays is crowded with papule and covered with a series of hemis- 
pherical, sometimes sub-spherical, spines with polished surfaces 
looking like round cobblestones. Crowded in between these are 
many smaller sub-globular spines, some of which seem to be dis- 
torted by over-crowding. 
The madreporie body is nearer the center than the margin of 
the disc, is somewhat irregularly oval in form with a longitudinal 
furrow in the center and very fine vermiform striations. On the 
lower surface the spines are like those on the dorsal side but eon- 
siderably smaller and here occasional two-pronged pedicellariz 
ean be detected while papule are absent. 
The ambulacral feet are in two rows and have very large, power- 
ful suckers. The ambulacral grooves are flanked by a row of 
